Note 21 - Incentive Plans - Performance Shares Significant Fair Value Assumptions (Details) - Performance Shares [Member] - $ / shares		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock price (in dollars per share)		$ 26.29	$ 26.83	$ 21.49
Dividend yield (1)	[1]	0.00%	0.00%	0.00%
Risk-free rate		0.87%	0.98%	0.65%
Volatility		18.80%	16.81%	25.93%
Term of the award (years) (Year)		2 years 321 days	2 years 321 days	2 years 321 days
Performance Share Issued 2 [Member]
Term of the award (years) (Year)			1 year 321 days	1 year 321 days
Performance Shares Issued 1 [Member]
Term of the award (years) (Year)				321 days

[1] Total Shareholder Returns, as used in the performance share awards computation, are measured based on cumulative dividend stock prices, as such a zero percent dividend yield is utilized.